| 其他摘要 | China locates at Circle-Pacific mercury mineralization belt. It has several large-scale and super large-scale mercury deposits. For example, Wanshan mercury mine in Guizhou, Wuchuan mercury mine in Guizhou, Chatian mercury mine in Hunan, Xiushan mercury mine in Chongqing, Xunyang mercury mine in Shanxi etc. However, those mercury mines were closed due to the exhaustion of natural resources and contamination of environment as a result of mercury mining and refining activities. The crops, which grown in mercury contaminated soil, have extremely high concentration of mercury in their edible part. The consumption of these mercury contaminated crops pose a great health risk to local inhabitants. Therefore, the remediation of mercury contaminated soil at mercury mine is necessary to insure the safety of crops and very important to maintain the eco-safety at mercury mine. At mercury mining area in China, large areas of soils were contaminated with mercury and these soils are distributed dispersive, thus it is difficulty to remediate ex-situ. The majority of mercury contaminated soil distributes at the village, far from the urban area, and is not deserved for investment, moreover, these soils are historically contaminated, and thus it is difficulty to encourage enterprise or individual to do remediation. Therefore, it is very important to explore the remediation techniques which are cheap and suitable for the current status of China. Many techniques have been proposed for remediation of heavy metals contaminated soils, such as stabilization/solidification, chemical immobilization, thermal desorption, electro-remediation, soil washing, phytostabilization, phytoextraction and phytovolatilization etc. Among these techniques, phytoextraction uses green plants to uptake pollutants from soil and move them to the aboveground tissues, and then harvest the plants through which the pollutants were removed. Phytoextraction is becoming more popular than other techniques in remediating heavy metals contamination soils due to its low cost, simple operation and can be used to treat large area contaminated land etc. In China, phytoextraction has been successfully used to remediate heavy metal contaminated soil in mining area. The main purposes of this thesis is trying to use phytoextraction to remediate mercury contaminated soils at Wanshan, and the main research contents including: the screen of mercury accumulator plants at Wanshan; the study of chemically assisted phytoextraction of mercury contaminated soil; ammonium thiosulphate induced Chenopodium glaucum to phytoextract mercury from Wanshan mercury contaminated soil; the characteristics of different plant species to accumulate mercury with thiosulphate amendment; phytoextraction of mercury contaminated soil-a field trial; the study of mechanism of plant uptake mercury with thiosulphate amendment. The main results are described as follows: 1. The study of mercury concentration in soils and plants collected from the main mines at Wanshan showed that the total mercury concentration in the soil greatly exceed the soil environmental quality standard Ⅲ set by Chiese EPA, the bioavailable mercury concentration in soil was very low, which only represent less than 0.25% of total mercury. |
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